In the United States, nearly 650,000 patients undergo coronary artery bypass grafting (CABG) each year. This procedure has been very successful in relieving the symptoms of coronary disease. However, CABG is also associated with a variety of neurological problems, ranging from stroke to cognitive changes and depression, and this remains a major cause of problems after surgery. Cognitive decline from 2 weeks to 2 months has been estimated between 30 and 79%. In addition, the possibility that CABG patients may have cognitive problems one or more years after surgery, has not been extensively investigated. The cause of these problems is uncertain but may be related to events that happen during the operation. This study will compare cognitive outcomes in 3 groups of patients from a pool of patients with coronary artery disease: 1) patients having conventional CABG; 2) patients having OPCABG or off-pump CABG, a procedure performed on the beating heart without the use of the cardiopulmonary bypass machine; and 3) patients who have diagnosed coronary disease, but have been managed medically. Patients will be evaluated using neuropsychological tests and measures of depression at three time points: preoperatively, at 3 months, and at one year. The long-term objective of this proposal is to determine the role of the cardiopulmonary bypass machine in cognitive change after CABG with the ultimate purpose of proposing interventions to overcome these adverse effects.